53 Pa. Stat. § 881.412
A municipality which has joined the retirement system created or continued under this Article IV may, for good and stated cause, file an application with the board for permission to withdraw from the system if it meets all of the following requirements:
The board shall within ninety days of its receipt, take action on an application filed by a municipality for permission to withdraw from the system. If the application is approved the withdrawing municipality shall be entitled to receive a net refund of the amounts then standing to the credit of the municipality in the member's account, the member's excess investment account, the municipal account, the subsidiary DROP participant reserve account and the retired member's reserve accounts of the system. In no event shall the total amount of the net refund to the municipality exceed the pro rata interest of the withdrawing municipality in the net assets of the entire fund based on the market value of the investments of the fund as of the date of receipt of the application for permission to withdraw. The liability for the continuation of retirement or disability allowances being paid from the fund shall attach against the withdrawing municipality and be paid from funds transferred to a retirement system established subsequent to its withdrawal from the system or from moneys appropriated annually from tax revenues sufficient to pay the same. If the board disapproves the application of the municipality for permission to withdraw from the system the board shall promptly notify the municipality of its decision and advise the municipality of the board's reason or reasons for disapproval. The board shall establish rules and regulations, in accordance with the provisions of clause (10) of section 104 of this act, governing the details of the procedures to be followed in the withdrawal of municipalities from the system.
53 P.S. § 881.412